Known in the art is to operate an elevator system by means of an elevator control system and at least one drive actuated by the elevator control system for moving at least one elevator car. The elevator control system controls the movement of at least one elevator car in at least one elevator car shaft. The or each elevator car—the description below will be continued based on one elevator car, without ruling out a more expansive general validity—approaches individual floors under the control of the elevator control system, and in the process stops at a respective floor in a prescribed stopping position. The prescribed stopping positions are derived based on the number of floors linked by the elevator car shaft, and based on a lower edge of the individual floor doors. A stopping position is then the position of the elevator car in the elevator car shaft in which the one lower edge of the floor door and a lower edge of the car door align, or at least essentially align.
The drive controlled by the elevator control system for moving the elevator car is usually a drive in the form of a converter fed by a supply network with an electric motor downstream from the converter. By actuating the motor-side portion of the converter (inverter) in a manner basically known in the art, the electrical power that gets to the electric motor is influenced in terms of frequency and amplitude, so that in particular the speed of the electric motor, and hence the resultant speed at which the elevator car moves in the elevator car shaft, can be influenced and prescribed by means of the elevator control system.
For purposes of the floor stop mentioned above, position information referred to below as the current position can be compared with a stopping position prescribed for the floor stop. The elevator control system receives the position information used as the current position from the drive. For example, data about the speed and rotational position of the drive are here involved. In a manner known in the art, electric drives make such data accessible for retrieval by an external controller, i.e., the elevator control system in this case. If the current position and stopping position coincide within prescribed limits, the stopping position has been reached. The elevator car is then in a position where the car doors can be opened for the respective floor, so as to allow passengers to exit or waiting passengers to enter. However, the desired stopping position can in practice not always be approached with the actually desired accuracy, which is termed landing precision in specialized terminology.